Glossary - SMA SUNNY ISLAND 4548-US Operating Manual

SMA Solar Technology America LLC 23 Glossary

23 Glossary

Absorption Phase
Constant voltage phase: A charging phase using constant charging voltage. The charging current
constantly decreases in this phase.
AC
Abbreviation for "Alternating Current"
AC Coupling
The AC side connection between loads, generators and storage devices.
AGM Battery
Absorbent Glass Mat separator battery. This is a battery where the electrolyte (a mixture of water and
sulfuric acid) is bound to a glass fiber mat. This is a type of a sealed or valve regulated lead-acid
(VRLA) lead-acid battery. A gas mixture (hydrogen and oxygen) is always generated when lead-acid
batteries are charged, and in normal operation this internally recombines to form water. This removes
the need for regularly refilling the battery cells with water, which is why these batteries are often
described as "low maintenance" or even "maintenance free". AGM batteries are available from many
different manufacturers for a wide range of applications. They usually have very good high current
properties but are not very charge-cycle resistant in relation to deep discharge.
Ah
Abbreviation for "ampere-hour". Unit of electrical charge, one ampere-hour is the charge provided by
a constant current of 1 A over a period of one hour.
AI
Abbreviation for anti-islanding. Procedure which prevents unintentional islanding on the utility grid.
Equalization Charge
Equalization charge: allows different series-connected battery cells to be charged to a unified state of
charge of 95% to 100%. Without regular equalization charge, the state of charge of the different
cells slowly drift apart, which can lead to a poor battery power performance and a premature battery
storage system failure.
Battery-Backup System
Backup-backup systems are power supply systems that provide an extra level of security for standard
power supply systems. The utility grid is usually the standard power supply system and the
battery-backup system which is protected by an additional stand-alone grid system in the case of a
power outage. In addition to the battery-backup systems, diesel generators in PV battery systems are
also described as backup generators. They perform the same task as a battery-backup system for the
utility grid.
Operating Manual SI4548-6048-US-BE-en-21 233